Rotary piston internal combustion engine

ABSTRACT

The rotary piston of an internal combustion engine has a geometrical configuration such that all lines through the axis of rotation of the piston are of equal length.

United States Patent [72] Inventor FredrIkJeremlasI-logguer [50]FieldolSearch 123/807, Nleuw Loosdrechtsedlik 264, Netherlands 8.35,8.41; 418/210, 240, 150 [21) AppLNo. 33,619 1221 Filed May 1,1970 1Rekmmcfled 4s Patented Nov. 30, 1971 UNITED STATES PATENTS [3 1Priorities Mas/2,1969 154,231 8/1874 Dietz 418 240x 3 Netherlands1,033,514 7/1912 A1fo1'd.. 418/240 [3 6906731; 1,157,806 10/1915 Rixen418/240 Dec-l9,l969.Nethrlands,N9-69l9089 1,944,956 1 1934 Thomas....4181240 2,215,873 9/1940 Gahm 418/240X 3,361,119 1/1968 COnOIly....41s/240x {54] ROTARY PISTON INTERNAL COMBUSTION ENGINE 8 Claims, 21Drawing Figs.

[52] US. l23/8.07, 123/835, l23/8.41, 4181210, 418/240,418/150 [51] Int.Cl ..F02h 53/06, F02b 55/08 Primary Examiner-Allan D. HemnannAttorney-Burns, Doane, Swecker 8: Mathis ABSTRACT: The rotary piston of,an internal combustion engine has a geometrical configuration such thatall lines through the axis of rotation of the piston are of equallength,

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SHEET 070F 10 PATENTEDuuvaomn 3,624,740 SHEET U80F 10 ROTARY PISTONINTERNAL COMBUSTION ENGINE This invention relates to an internalcombustion engine comprising an engine housing having a virtuallyright-circular cylindrical inner wall, a rotary, out-of-round,cylindrical, hollow piston within said housing, pairs of diametricallyopposed slides guided in fixed parts of said housing for radial movement and continuously in contact with the periphery of said piston todefine sections of varying radial dimensions between said housing andsaid piston for different phases of the combustion process, the slidesof each pair being interconnected by a diametrical coupling rod.

An engine of this kind, hereinafter referred to as of the kinddescribed, is known, and has various disadvantages, the most importantone of which is that the shape of the periphery of the piston makes itnecessary for the coupling rods of the pairs of slides to be providedwith a resilient member to ensure that the slides are always in contactwith the piston.

It is an object of the present invention to provide an improvedconstruction of the engine, thereby to overcome these and otherdisadvantages.

According to the invention, there is provided an internal combustionengine of the kind described, in which the crosssectional configurationof the peripheral wall of the piston is composed of two opposedquadrants of a circle having a common center in the axis of rotation ofthe piston and respectively having a larger radius R and a smallerradius r, said quadrants being connected by arcuate portions in theother quadrants, whose geometrical configuration is the locus of pointsto be found by drawing in one of the last-mentioned quadrants anauxiliary arc of a circle having a radius r and having its center in theradius bounding the larger of said firstmentioned quadrants and thequadrant in which the auxiliary arc is drawn, and at a distance R-r fromthe axis of rotation of the piston, drawing a diametral line R+r fromeach point of said auxiliary circle through the center of saidfirst-mentioned quadrants, producing said diametral line to a secondauxiliary circle in the opposite quadrant, said second auxiliary circlehaving a radius r and having its center in the other radius boundingithelarger of said first-mentioned quadrants and at a distance R-r from theaxis of rotation of the piston and bisecting the line by which saiddiametral line is produced.

It is thus achieved that, as a result of the fact that all diametrallines through the axis of rotation of the piston, or, in space, therectangular diametral planes of the piston are of equal length, thecoupling rods may be rigid, provided their coefficient of expansion beequal to that of the material of the piston.

In one embodiment of the invention, in which the engine is of thefour-stroke type, the inner periphery of the housing is defined by aninscribed right-circular cylinder having a radius of curvature equal tothat of the piston sector having the larger radius of curvature,increased by the compression space.

In another embodiment of the invention, in which the engine is of thetwo-stroke type, the peripheral wall of the piston is of virtuallyuniform thickness throughout, and also has radial pairs of slidescontinuously in contact with its inner periphery, said slides beingguided in slots of a centric, solid core in the form of a solid ofrevolution and fixedly connected with the housing of the engine, theinner periphery of the piston located closest to the center passingalong the basis of said core, a thick, crescent-shaped disk, boundingone flat piston wall and extending halfway the other flat piston beingsecured to the peripheral wall of the piston, and having a centricright-circular cylindrical circumference, and except for the portion ofthe outer periphery of the piston which passes along the cylindricalwall of the housing, extends outside the other portions at the outerperiphery of the piston, and is provided with an outlet, the flat pistonsurface at the upper side of the core having an inlet, the peripheralwall of the piston having a passage opening adjacent to, but trailingrelative to, said outlet.

The invention will now be described with reference to the accompanyingdrawings, which, inter alia, illustrate a nonlimitative embodiment of afour-stroke engine and a twostroke engine. In said drawings,

FIG. 1 shows a diagram according to which both the outer circumferenceand the inner circumference of the piston according to the invention aredesigned, the latter circumference being of interest for a two-strokeengine;

FIG. 2-9 are diagrammatic showings of the internal combustion engineaccording to the invention, showing various phases of a four-strokeprocess;

FIG. 10-16 are diagrammatic showings of an internal combustion engineaccording to the invention, showing various phases of a two-strokeprocess;

FIG. I7 is an axial sectional view of an embodiment of a four-strokeengine according to the invention, with two pistons in the sameposition, namely, on the line XVII-XVII of FIG. 18;

FIG. 13 is a cross-sectional view of the engine of the line XVIIIXVIIIof FIG. 17;

FIG. 19 shows, on a slightly enlarged scale, an axial section of anembodiment of a two-stroke engine according to the invention on the lineXlX-X of FIG. 20, the upper half of the section being turned throughrelative to the lower half;

FIG. 20 and 21 are two cross-sectional views of the engine on the linesXXXX and XXIXXI, respectively, of FIG. 19.

Referring particularly to FIG. '1, both the four-stroke and thetwo-stroke engine require such a peripheral configuration of the pistonthat slides coupled pairwise by means of a rigid coupling rod arecontinuously in contact with the periphery of the piston, which couplingrod intersects the axis of rotation according to diametral lines. Forthis purpose, all diametral lines must be equally long. 7

The peripheral configuration of the hollow piston, generally indicatedat l, and as viewed in cross section, is composed of two opposingquadrants of circles, namely arcs 2 and 3, respectively having a largerradius R and a smaller radius r. The two arcs 2 and 3 are interconnectedby transitional arcs 4, 4'.

The configuration of the transitional arcs is determined by drawing twoadditional quadrants of a circles, namely rightand left-hand auxiliaryarcs 5 and 5' having centers 0, 0' and a radius r and beginning at theends of the arc with radius R. Virtually straight lines 6 connect theauxiliary arcs 5, 5' having a radius r with the arc 3.

On the horizontal diametral line 7 a line having a length R+r is setofi' from the left-hand auxiliary arc 5' in FIG. 1 to determine point 8.The middle 9 of the line between 8 and the righthand auxiliary arc is apoint of the right-hand transitional are 4. In the same way other pointsof the transitional arcs are determined by drawing other diametral linesand setting off R+r either from the left-hand or from the right-handauxiliary arc.

The radii R and r in FIG. 1 concern the inner periphery of the wall ofthe piston.

The outer circumference of the piston wall can be designed in the samemanner. It is simpler, however, when thickness d is set off radiallyoutwardly from the inner arcs on the diametral lines. It follows thatthe thickness of the peripheral wall of the piston varies slightly andis greatest where the diametral lines intersect the circumference atright angles, in other words where they are perpendicular to the tangentat that point.

There will now follow a description of the four-stroke process of theengine according to the invention with particular reference to FIG. 2-9.

In FIG. 2-9, numeral 10 designates the inner circumference of the wallof the housing, sometimes referred to as the cylinder, and l the rotarypiston. The inner circumference 10 is determined by an inscribed circlewhich in FIG. 2-9, owing to the diagrammatic representation largelycoincides with the inner circumference.

The piston 1 has two circumferential sections 2, 3 in the form of an arcof a circle concentric with the inscribed circle and respectively havinga larger radius R and a smaller radius r. The arcs with radius R and r,respectively, define opposing sectors l1, 12, each having an angle atthe center or axis of rotation 13 of 90. The two other sectors 14,naturally also have an angle at the center of 90, and are defined bytransitional arcs 4, 4'.

The dot-dash lines in FIGS. 2-9 which define the sectors are the radialaxes of movement of slides, two of which are shown diagrammatically at16, 17. There are further four pairs of poppet valves in the housing,one pair 18, 19 of which is shown, 18 being an inlet valve and 19 anoutlet valve. Finally, there is shown a diagrammatic spark plug disposedbetween valves 18 and 19.

In the quadrant between slides 16, 17, which are continuously held incontact with the circumference of the piston, a complete four-strokeworking process takes place, as a result of which the piston rotates inthe direction of arrow 21.

The Z-shaped arrow 22 in FIG. 2 indicates ignition, it being supposedthat there is a compressed explosive mixture in the quadrant between thepiston and the inner wall of the housing.

Owing to the rotation of the piston, initiated by a starting motor notshown, the space 23 between the piston and the cylinder is increased(see FIG. 3) and expansion occurs". The forces generated are such as tomove the arc 4 of the piston, this being the only member which can movein this space, and thereby to impart a rotary impulse to the piston.

The piston rotates further, whereby the concentric are 3-- the arcs 4',3, 4 can be regarded as the inner arc of a virtually crescent-shapedportion removed from an originally truly circular pistoncomes to lieopposite valves 18, 19. Since further expansion is impossible, becausethe space 23 has reached its maximum volume, the outlet valve 19 beginsto open (FIG. 4). Expulsion continues as the piston rotates along,thevalve 19 reaching its maximum opening in FIG. 5. Expulsion ispromoted owing to the space 23 being decreased in size again by the are41.

In the position of the piston of FIG. 6-which is equal to that of FIG. 2and comparable to the outer dead center of a A crank connecting rodpiston enginethe outlet valve 19 is closed and the inlet valve 18 beginsto open.

As the piston I rotates further, the space 23 is again increased owingto the movement of transitional are 4 and when the inlet valve 18 isfully open, the inlet phase is accomplished, in other words, air or acombustible mixture-depending on whether the engine works according tothe diesel principle or the Otto principle, is drawn into the space 23(FIG. 7).

The end of the inlet phase is shown in FIG. 8, in which Figure the inletvalve is shown as being closed.

Finally, after the inlet valve-and also the outlet valve-are fullyclosed, compression occurs owing to the fact that the volume of thespace 23 is again reduced by the transitional arc (FIG. 9). After onefurther quarter revolution ofthe piston, ignition can again occur, andthe situation of FIG. 2 has been reached.

In FIGS. 29, arrows are shown at the valve rods, which indicate thedirection of movement of the valves.

There will now follow a description of the two-stroke process of theengine according to the invention with reference to FIGS. 10-16.

FIG. 10 shows the beginning of the power stroke resulting fromcombustion or explosion which has just occurred owing to sparking fromthe spark plug 20. The combustion chamber 23 is bounded by the cylinderwall 10 of the engine housing, the circumferential surface of the piston1 and two outward radial slides 16 and 17. The slides 16 and 17 eachform part of a diametrally coupled pair of slides, the slides on theopposite sides being designated by 16 and 17. The direction of rotationof the piston is indicated by arrow 21.

FIG. 11 shows the power stroke in full operation. Owing to the wideningspace 24, expansion of the combusted gases takes place. The power strokeends when the outlet port has passed slide 16. This is shown in FIG. I2.The outlet port is arranged in a thick disk to be described hereinafter.The disk is connected with the circumferential wall of the piston I andis also active as a balancing weight. Consequently the outlet port 25rotates along with the oubof-round piston wall.

In the position shown in FIG. 12, a passage opening 26 is located justbefore the slide 16as seen in the direction of rotation according toarrow 21-in the piston wall. Through the passage opening 26, the innerspace 27 of the piston communicates with the outside chambers. Disposedin the inner chamber of the piston is a fixed, centrally arranged solidcore 28, preferably in the form of a solid of revolution, which will bedescribed later. This core defines with the piston wall a space 29,which is widened as the piston rotates, as shown in FIG. 13. The chamber29 is further bounded by two radial slides 30 and 3I-disposed within thepiston-which together with slides 30' and 31' respectively form anintegral diametral pair of slides whose direction of to and fro movementcoincides with that of the outward pairs of slides 16, I7 and 17, 17,respectively.

As shown in FIG. 13, the widening chamber 29 comes in communication withthe inlet port 32 of the piston, which is in continuous communicationwith the air and fuel mixture inlet of the engine, to be describedhereinafter. Accordingly, there is intake of fresh mixture within thepiston.

In the position shown in FIG. 14, the piston has rotated so far thatexpulsion via port 25 from the space between the slides 16 and 17terminates, and intake into the spaces between the inward slides 30, 31,30' via port 32 is in full progress.

An earlier intake of mixture in the space 33 between the wall of pistonl, the body 28, and the slides 30 and 31 which has been compressed inthe restricted space 33 in FIG. l3 referred to as precompressionnowflows through the space 34 outside the piston wall and between theslides 16 and 17, in which at the end of the exhaust period a lowerpressure prevails than in the inner space 33.

In the position of FIG. 14, the outer space 34 begins to decrease involume, and after the passage opening 26 has passed slides 17, 31 asshown in FIG. 15, compression is continued in this space. In theposition of FIG. 13, in which the outlet port 25 and the passage opening26 are between the same slides 16 and 17, the mixture flowing viaopening 26 into the space 34 will expell the remainder of combustedgases through the outlet port 26. This is the scavenging, which is ofthe greatest importance in a two-stroke engine.

In the position according to FIG. 16, compression outside the pistonwall and intake within the piston wall continue until the position ofFIG. 10 is reached, followed by ignition and explosion, initiating thepower stroke.

The above described process takes place between slides 16 and 17 (30 and31'). At the same time it takes place between slides 17 and 16' (3! and30'), 16' and 17' (30' and 3I) and finally between slides 17 and 16 (31and 30), that is, four times in one revolution of the piston.Accordingly, there are four power strokes per revolution of the pistonwithout an interruption during the next revolution, as would be the casein a four-stroke engine with a single rotary piston.

There will now follow a description of an embodiment of a four-strokeengine according to the invention with particular reference to FIGS. 17and 18. As appears from the description of FIG. 2-9, this engine workswith two pairs of slides and four pairs of valves. In FIGS. 17 and I8and 29, like parts are designated by the same reference numerals. InFIG. 17, the engine is provided with two equally positioned pistons I,I, rotating within a common cylindrical wall 10 of the engine housing.The rotary shaft consists of three sections, namely, shaft 13 whichconnects the two pistons, and the ends of which are provided with keygrooves 35 which engage with countergrooves of hub members 36, thelatter being connected with the facing piston walls 38 by means ofbolts, of which the axes 37 are shown only. The piston walls 39 facingaway from each other are provided with hollow taps 40 in an alignmentwith shaft 13, which taps constitute the two other sections of the shaftand are journaled in roller bearings 41 for rotation relative to outwardcylindrical stubs 42 of the flat sidewalls 43 of the engine housing. I

The connecting shaft 13 is journaled in roller bearings 46 via bearingblocks 45 relative to the fixed partition wall 44.

The radially reciprocating slides cooperating with the peripheral wallsof the pistons, one pair of which is shown connected by a connecting rod47 with a slot 48 for the passage of shaft 13, are provided with means,such as flat springs (not shown) to urge them into sealing slidingcontact with the peripheral wall of the respective piston in cooperationwith a lubricant film and allowing for some clearance owing to thermalinfluences. A cross section of the other connecting rod 47, providedwith a slot 48, is to be seen in FIG. 17.

The slides 16, 16' (and also the slides 17, 17', not visible in FIG. 17)are constituted by two wings 49, 50, formed integrally with each other.Since connecting rod 47, 47' of each pair of slides engages slightlyeccentrically, so that there is a risk of warping, the free ends of thewings are received in radial grooves 51 in the sidewalls 43 of theengine housing.

The poppet valves, of which in FIG. 18 the rods of the uppermostassociated pair are designated by 18 and 19, are not shown in FIG. 17.The latter figure only shows the upper parts of the valve springs 52,spring cups 53, rockers 54, and tappets 55. The valves on the right-handside and on the left-hand side have their axes respectively located inone plane perpendicular to the axis of rotation. However, the tappets ofthe inlet valves are axially offset relative to the tappets of theoutlet valves through a distance 56, as a result of which all outletvalves and all inlet valves can each be operated by a single cam 57, 58.In this way, all rockers are of equal length, resulting in an equallifting height. (In FIG. 17, reference numerals 52 and higher are onlyshown in the right-hand half).

Cams 57 and 58 are arranged on a sleeve 59 freely rotatable on hollowtaps 40. Sleeve 59 carries a gear wheel 60 at its end, which 2:1 with asprocket 61 which with a sprocket 62 is keyed to an intennediate shaft63. Shaft 63 is joumaled for free rotation in a case 64 extendingradially from stub 42. The last-mentioned sprocket 62 engages with asprocket 65 keyed to tap 40. This established the 2:1 ratio of therotation of the cams and the piston.

On account of their eccentricity, the pistons are each provided with abalancing weight 66, cast in one piece with the piston. When the pistonsconsist of welded together pieces of metal plating the balancing weightmay be a separate member.

In the zone of the valve cups, the inner wall of the cylinder is formedas a regular polygon 67, but axially beside the valve cup zone as aright-circular cylinder 68.

The slide compartments 70 are closed with covers 69, while the outwardlyflaring tubes 71 in the hollow taps are designed for passing coolingfluid to the interior of the piston, which fluid can flow back throughthe annular space 72 between the tubes and the tap wall.

The two-stroke embodiment of the engine according to the invention willnow be described in greater detail. This engine operates as describedwith reference to FIGS. -16. The reference numerals used in thesefigures are also used in FIGS. 19, 20, and 21 for designating likeparts.

In the two-stroke rotary engine, the piston 1 is divided into two axialparts 73 and 74, secured together. A ring 77 of radially varyingthickness and right-circular cylindrical circumference is secured tosidewall 75the left-hand one in FIG. 19*of the part 73 by means of bolts76, which ring surrounds the peripheral wall of the piston proper andacts as a balancing weight. The balancing weight has its largestthickness at 78.

In the part 73 of the piston (see FIGS. 19 and the inner surface of thecircumferential wall of the piston is in cooperation with internalslides 30, 31 and 31', the outer surface of the piston wall of part 74being continuously in contact with external slides 16, 16', 17 and 17'.Each internal pair of slides forms an integral piece by means of anintermediate member 79, 79 half as wide as the slides, the externalslides being pairwise coupled by coupling rods 47, 47' with threadedends 80 and adjusting nuts 81, in the same way as in the four-strokeengine, and being guided in recesses 82, 82 in the central core 28,which in the subject embodiment is truly right-circular cylindrical.

This core extends axially throughout the two parts 73, 74 of the pistonand is secured to wall 84 of the engine housing bounding part 74 bymeans of a central tap bolt 83. An eccentrically disposed pin 85restrains the core from rotating along with the piston.

Unlike the four-stroke engine of FIGS. 17 and 18, the twostroke enginehas a single piston, composed of two different parts 73, 74, and theslides 16, 16', 17 and 17' are guided by round pins 86 formed integrallywith covers 69.

The piston part 74 (see FIGS. 19 and 21), has no slide in its interiorand its peripheral wall may have a thickness different from that of part73, which is designed in accordance with FIG. 1. Part 74 is providedwith some oil baffles 87, by means of which the wall is connected withcentral bushing 88. This bushing is journaled on an inwardly extendingstub 92 of the wall 84 of the engine housing by means of a double-needlebearing with needles 89, and intermediate ring 91. The outside openingof stub 92, which has an intermediate wall 93 as a supporting surfacefor tap bolt 83, is closed with a cover 94, which is clamped againstwall 94 by tap bolts 95. The sidewall 97 of piston part 74 is sealed bymeans of a flat, broad stationary ring 96.

The sidewall 98 of piston part 73 is connected with a shaft 100 by tapbolts 99, from which shaft the power of the engine can be taken off.Shaft 100 is journaled by means of needle bearing 101 in an inlet stub102 with a lip 103, which forms part of the wall 104 of the enginehousing.

At the flanged portion 105 of shaft 100, through which the tap bolts 99are inserted, the shaft is provided with a central, stepped, blind bore106, in which is arranged a ball bearing 107, which supports thestationary core 128 via a connecting member 108 secured to the bore bytap bolts 109.

FIGS. 19, 20 and 21 clearly show inlet port 32, passage 32 and outletport 25.

The interior of the piston is cooled by a suitable fluid which entersthrough a supply tube not shown and can flow away through a dischargetube 110. For this purpose, ring 96, stub 92 and sidewall 97 of thepiston are provided with passages 1 1 1.

112,113, 114, designate connecting pins, and 116, 117, 118, 119, 120,121, 122 designate suitable sealing means. The latter may be gaskets,resilient plates or elastic insertions, grease gaskets, and like means.

The engine housing consists of two halves, each having a sidewall 104,82 and a circumferential portion 123, 124, formed integrally therewith,and through which extend long connecting bolts not shown.

In the four-stroke engine according to the invention, combustion takesplace four times in succession during each revolution with one pistonand, owing to the second piston, again four combustions during the nextrevolution. Each piston must perform one revolution for intake andcompression.

In the two-stroke engine with one piston, there are four explosionsduring each revolution, that is, eight explosions in two revolutions. Inthis embodiment the volume of the inner space between the piston walland the core is larger than the volume of the outer space between theinner wall of the housing and the piston wall.

It will be clear that modifications can be made in numerous minordetails without departing from the scope of the invention.

lclaim:

1. An internal combustion engine comprising an engine housing having avirtually right-circular cylindrical inner wall, a rotary, out-of-roundcylindrical, hollow piston within said housing, diametrically opposedpairs of slides guided in fixed parts of said housing for radialmovement and continuously in contact with the periphery of said pistonto define sections of varying radial dimensions between said housing andsaid piston for different phases of the combustion process, the slidesof each pair being interconnected by a diametral coupling rod, in whichthe cross-sectional configuration of the peripheral wall of the pistonis composed of two opposed quadrants of a circle having a common centerin the axis of rotation of the piston and respectively having a largerradius R and a smaller radius r, said quadrants being connected byarcuate portions in the other quadrants, whose geometrical configurationis the locus of points to be found by drawing in one of thelast-mentioned quadrants an auxiliary arc of a circle having a radius rand having its center in the radius bounding the larger of saidfirst-mentioned quadrants and the quadrant in which the auxiliary arc isdrawn, and at a distance R-r from the axis of rotation of the piston,drawing a diametral line R+r from each point of said auxiliary circlethrough the center of said first-mentioned quadrants, producing saiddiametral line to a second auxiliary circle in the opposite quadrant,said second auxiliary circle having a radius r and having its center inthe other radius bounding the larger of said first-mentioned quadrantsand at a distance. R-r from the axis of rotation of the piston, andbisecting the line by which said diametral line is produced.

2. An internal combustion engine according to claim 1 and operatingaccording to the four-stroke principle, wherein the inner periphery ofthe housing is defined by an inscribed rightcircular cylinder having aradius of curvature equal to that of the piston sector having the largerradius of curvature, increased by the compression space.

3. An internal combustion engine according to claim 1, characterized inthat a pair of radially movable valves is arranged between each pair ofsuccessive slides, said valves being preferably formed as poppet valves,and controlling an inlet channel and an outlet channel, the flat sidesof the valve cups facing the piston forming with the adjacent parts ofthe inner circumference of the wall of said housing a polygon with whichthe inscribed right-circular cylinder is locally in contact.

4. An internal combustion engine according to claim 1, comprising twoequally positioned pistons, and wherein each slide is duplicated to besimultaneously in contact with both peripheral walls of the piston, theconnecting rods of each pair of slides engaging with the slides adjacentthe middle, and extending between the two pistons said rods having aslot through which extends the rotary shaft connecting the two pistons.

5. An internal combustion engine according to claim 1, and operatingaccording to the two-stroke principle, in which the peripheral walls ofthe piston is of virtually uniform thickness throughout, and also hasradial pairs of slides continuously in contact with its inner periphery,said slides being guided in slots of a centric, solid core in the formof a solid of revolution and fixedly connected with the housing of theengine. the inner periphery of the piston located closest to the centerrubbing along the basis of said core, a thick crescent-shaped disk,bounding one fiat piston wall and extending halfway the other flatpiston wall, being secured to the peripheral wall and having a centricright-circular cylindrical circumference, and except for the portion ofthe outer periphery of the piston which rubs along the cylindrical wallof the housing, extends outside the other portions at the outerperiphery of the piston, and is provided with an outlet, the flat pistonsurface at the upper side of the core having an inlet, the peripheralwall of the piston having a passage opening adjacent to, but trailingrelative to, said outlet.

6. An internal combustion engine according to claim 5, wherein tworadially inward pairs of slides and two radially outward pairs of slidesare provided, which together with the inner circumference of the pistonand the core define an intake chamber, a transition chamber and aprecompressing chamber, and with the outer circumference of the pistonand the cylinder wall define an intake chamber, and end compressionchamber, and an expansion chamber, respectively.

7. An internal combustion engine according to claim 6, wherein theinward pairs of slides consist of a single integral rece. p 8. Aninternal combustion engine according to claim 5 wherein the volume ofthe inner space between the piston wall and the core is larger than thevolume of the outer space between the inner wall of the housing and thepiston wall.

* I i l

1. An internal combustion engine comprising an engine housing having avirtually right-circular cylindrical inner wall, a rotary, out-of-roundcylindrical, hollow piston within said housing, diametrically opposedpairs of slides guided in fixed parts of said housing for radialmovement and continuously in contact with the periphery of said pistonto define sections of varying radial dimensions between said housing andsaid piston for different phases of the combustion process, the slidesof each pair being interconnected by a diametral coupling rod, in whichthe cross-sectional configuration of the peripheral wall of the pistonis composed of two opposed quadrants of a circle having a common centerin the axis of rotation of the piston and respectively having a largerradius R and a smaller radius r, said quadrants being connected byarcuate portions in the other quadrants, whose geometrical configurationis the locus of points to be found by drawing in one of thelast-mentioned quadrants an auxiliary arc of a circle having a radius rand having its center in the radius bounding the larger of saidfirst-mentioned quadrants and the quadrant in which the auxiliary arc isdrawn, and at a distance R- r from the axis of rotation of the piston,drawing a diametral line R+ r from each point of said auxiliary circlethrough the center of said first-mentioned quadrants, producing saiddiametral line to a second auxiliary circle in the opposite quadrant,said second auxiliary circle having a radius r and having its center inthe other radius bounding the larger of said first-mentioned quadrantsand at a distance R-r from the axis of rotation of the piston, andbisecting the line by which said diametral line is produced.
 2. Aninternal combustion engine according to claim 1 and operating accordingto the four-stroke principle, wherein the inner periphery of the housingis defined by an inscribed right-circular cylinder having a radius ofcurvature equal to that of the piston sector having the larger radius ofcurvature, increased by the compression space.
 3. An internal combustionengine according to claim 1, characterized in that a pair of radiallymovable valves is arranged between each pair of successive slides, saidvalves being preferably formed as poppet valves, and controlling aninlet channel and an outlet channel, the flat sides of the valve cupsfacing the piston forming with the adjacent parts of the innercircumference of the wall of said housing a polygon with which theinscribed right-circular cylinder is locally in contact.
 4. An internalcombustion engine according to claim 1, comprising two equallypositioned pistons, and wherein each slide is duplicated to besimultaneously in contact with both peripheral walls of the piston, theconnecting rods of each pair of slides engaging with the slides adjacentthe middle, and extending between the two pistons said rods having aslot through which extends the rotary shaft connecting the two pistons.5. An internal combustion engine according to claim 1, and operatingaccording to the two-stroke principle, in which the peripheral walls ofthe piston is of virtually uniform thickness throughout, and also hasradial pairs of slides continuously in contact with its inner periphery,said slides being guided in slots of a centric, solid core in the formof a solid of revolution and fixedly connected with the housing of theengine, the inner periphery of the piston located closest to the centerrubbing along the basis of said core, a thick crescent-shaped disk,bounding one flat piston wall and extending halfway the other flatpiston wall, being secured to the peripheral wall and having a centricright-circular cylindrical circumference, and except for the portion ofthe outer periphery of the piston which rubs along the cylindrical wallof the housing, extends outside the other portions at the outerperiphery of the piston, and is provided with an outlet, the flat pistonsurface at the upper side of the core having an inlet, the peripheralwall of the piston having a passage opening adjacent to, but trailingrelative to, said outlet.
 6. An internal combustion engine according toclaim 5, wherein two radially inward pairs of slides and two radiallyoutward pairs of slides are provided, which together with the innercircumference of the piston and the core define an intake chamber, atransition chamber and a precompressing chamber, and with the outercircumference of the piston and the cylinder wall define an intakechamber, and end compression chamber, and an expansion chamber,respectively.
 7. An internal combustion engine according to claim 6,wherein the inward pairs of slides consist of a single integral piece.8. An internal combustion engine according to claim 5 wherein the volumeof the inner space between the piston wall and the core is larger thanthe volume of the outer space between the inner wall of the housing andthe piston wall.